(1) Field of the Invention
The present invention relates to a process for producing daunomycin, and more particularly, to a microbial process for producing daunomycin having the general formula (I) ##STR1## by culturing in a nutrient medium a mutant strain belonging to the genus Streptomyces capable of producing daunomycin and incapable of producing daunomycin analogues, said mutant strain being derived from strains belonging to the genus Streptomyces capable of producing daunomycin and analogues thereof simultaneously, and recovering daunomycin thus produced therefrom.
(2) Description of the Prior Art
A number of anthracycline glycosides have been described in prior literature. Among them, daunomycin is particularly being watched with keen interest by those in the field of cancer chemotherapy and has already been applied clinically for human cancers. Preparation of daunomycin by fermentation of Streptomyces peucetius N.C. I.B. 9475, of Streptomyces griseus var. rubidofaciens DS 32041, and of Streptomyces bifurcus DS 23219 is disclosed in U.S. Pat. No. 4,012,284. Chemical conversion of antibiotics complex produced by fermentation of Streptomyces coeruleorubidus NRRL 3045 and 3046 to daunomycin is disclosed in U.S. Pat. No. 3,989,598. However, as reported in J. Antibiotics 30, 619-621, 622-624, 1977 of the baumycins production by fermentation of Streptomyces coeruleorubidus ME 130-A4 which is known as a daunomycin-producing strain, the daunomycin-producing strains disclosed in said publications produce and accumulate in the broth as the final products daunomycin and analogues thereof simultaneously so that the recovery of daunomycin from the cultured broth needs a process of hydrolysis of daunomycin analogues to daunomycin by acidic treatment.
In the continuation of studies on fermentative production of daunomycin, the present inventors obtained a mutant strain which is capable of producing daunomycin and incapable of producing daunomycin analogues, from a daunomycin and baumycin-producing strain, Streptomyces coeruleorubidus ME 130-A4 (FERM P-3540), and succeeded in direct fermentative production of daunomycin without any process of acidic hydrolysis of daunomycin analogues.